The present invention relates to a device and method for generating alerting signals in a memory mode of a paging receiver when the battery of the paging receiver is a in low voltage state.
Generally, a paging receiver produces alerting signals indicative of the fact the same paging receiver is called, when receiving message data. The alerting signals are produced in the forms of an audible tone and vibration in normal and memory modes, respectively, as desired by a user. Referring to FIG. 1 in a conventional paging receiver, the user may set the paging receiver to the normal or memory mode through a switching circuit 115. A mode signal detector 114 transfers a normal mode signal or a memory mode signal to a controller 110 according to a selected mode.
The controller 110 periodically analyzes data received through a radio frequency (RF) receiver 121 so as to check out self data. Receiving the self data in the normal mode, the controller 110 stores the received self data into an internal memory and notifies the user of the call via a display 116 and a buzzer 118. However, if the controller 110 detects in memory mode the self data by analyzing the data received via the RF receiver 121, the controller 110 stores the self data into the internal memory, driving the display 116 and a motor 120, so as to notify the user of the call. In this case, the buzzer 118 is not driven.
A voltage detector 113 checks out a voltage state of the battery 11 for supplying power to the paging receiver, so as to generate a low voltage detection signal applied to the controller 110 when the battery voltage is in a low level. In this case, the controller 110 drives the buzzer 118 or motor 120 according to whether the normal mode or memory mode is selected.
In such a conventional paging receiver, the controller 110 periodically drives the motor 120 or buzzer 118 according to the selected mode even when the battery voltage is in the low level, thus accelerating the voltage consumption of the battery. Particularly in the memory mode, the motor 120 is periodically driven regardless of the voltage level of the battery, the excessive current for abruptly driving the motor 120 possible resulting in a sudden voltage drop of the battery so as to cause the initialization of the controller 110, so that it may be impossible to receive data as well as delete the data stored in the internal memory.
In order to resolve such problems there is proposed a method in U.S. Pat. No. 4,755,816 issued Jul. 5, 1988 to Motorola wherein if the voltage level of the battery is checked out to be insufficient before driving the alert device, the tone level of the alert device for notifying the user of the call is decreased in order to save the battery power.
However, in this prior art, the alert device is driven whenever the self data is received, and the voltage level of the battery is gradually decreased even though the self data is not received, so that it is impossible to detect the precise moment at which the voltage of the battery reaches the low level. Moreover, since the level of the alerting tone is adjusted at the moment when the self data is received, it is impossible for the user to exactly perceive that the voltage of the battery is in the low level.